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    <script>
        // 求两个数之间的和
        function count(a, b) {
          let fn = (j, x) => new Array(j).fill().map((i,idx) => idx + x).reduce((a, b) => a + b)  
          return a > b ? fn(a,b ) : fn(b, a)
        }
        let res = count(3, 1)
    </script>
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